Glutathione Peroxidase Response to Selenium Intake in Lambs Fed a Torula Yeast-Based, Artificial Milk

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Abstract
An 8-week experiment was conducted with 16 newborn lambs fed a Torula yeast-based, low selenium (Se), liquid diet (.01 ppm Se) supplemented on the basis of air-dried solids with 0, .05, .10 or .50 ppm Se supplied as Na2SeO3. The objective was to determine the effect of dietary Se intake on tissue glutathione peroxidase activity and Se concentration. Since glutathione peroxidase is a selenoenzyme, it was postulated that activity of this enzyme in tissues might be an index of Se adequacy. Dietary Se supplementation increased Se concentration and glutathione peroxidase activity in 10 different tissues analyzed, but some tissues responded more dramatically than others. In all tissues analyzed except pancreas and erythrocytes, glutathione peroxidase activity reached a plateau at approximately .11 ppm Se, but Se content of the tissues increased with each increment of dietary Se. Body weight gain and feed utilization were significantly (P<.05) lower in the basal group, however, no significant difference was observed in these parameters between the three supplemented groups. Tissue glutathione peroxidase was a better indicator of dietary Se adequacy than was tissue Se concentration. By this criterion, a total of .11 ppm Se on an air-dried solids basis (∼.12 ppm Se on a dry matter basis) satisfied the Se requirement of lambs fed the Torula yeast-based artificial milk diet but .06 ppm Se did not. Copyright © 1976. American Society of Animal Science . Copyright 1976 by American Society of Animal Science.